//
// Created by user on 2022/2/24.
//
#include <string>
#include <vector>
using namespace std;
char findTheDifference(string s, string t) {
    int ret = 0;
    for (char c:s)ret^=c;
    for (char c:t)ret^=c;
    return ret;
}

char findTheDifference1(string s, string t) {
     vector<int> count(26);
     for (char c:s)count[c-'a']++;
     for (char c:t){
         count[c-'a']--;
         if(count[c-'a']<0)return c;
     }
}